Also backfat lipid, and linoleic and linolenic acid mass were overestimated by the model. Backfat stearic and oleic acid composition were systematically overestimated whereas palmitic and linoleic acid were underestimated. Predicted values for the other FA were reasonable but these only represent 50 g/kg of the total FA. As for the body lipid, the model largely overestimated the perinephric lipids (>45%) and the corresponding linoleic and linolenic acid mass (Table 5). The FA composition was rather different from the results for all diets although the composition for the poly-unsaturated FA was reasonably well predicted. Differences concern mainly de novo synthesized FA; palmitic and stearic acid contents were largely underestimated (20%) whereas oleic acid content was overestimated (>35%).